Southwater was a station on the line built by the London Brighton and South Coast Railway in 1861 to link Horsham to Shoreham. This connecting line left the mid Sussex main line at Itchingfield Junction just south of Christ's Hospital Station. Another proposed line was promoted in 1865 to run to Worthing from a junction at Southwater which envisaged trains using the South Fork at Stammerham Junction (Christ's Hospital) to run through from Guildford. There was an extensive brickworks at Southwater and cement works at Beeding that made use of the railway until closure of the line in 1966. Both works were closed in the mid 1980s.
The model assumes that the line and the brick and cement works both remained open and modernised. The extensive housing that has developed in Southwater in recent years resulted in the line being electrified from Itchingfield Junction to Southwater and a DEMU service operating on to Shoreham and Brighton. The layout is set in the last quarter of the 20th century.